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Re: [linux-lvm] Apparent performance degradation for each PV with striping



On Sun, Mar 18, 2001 at 10:11:29PM -0700, Donald Thompson wrote:
> I started playing with iostat tonight and saw a few things I didn't
> really expect to see.
> 
> I've got a volume group consisting of 4 82 gig drives. All 4 are IDE
> drives.  Reading directly from the raw device, a PV in this case, with
> something like
> 
> dd if=/dev/ide/host0/bus0/target0/lun0/disc of=/dev/null

	Have you played with hdparm to try to tune the way the kernel
talks to your IDE drives?

	That may be the reason for being CPU bound.  The kernel tends to
default to the slowest possible method because there are a lot of bad
IDE controllers and drives out there that will trash your data if you
try to talk to them in a way they aren't expecting.

Have fun (if at all possible),
-- 
The best we can hope for concerning the people at large is that they
be properly armed.  -- Alexander Hamilton
-- Eric Hopper (hopper omnifarious mn org http://www.omnifarious.org/~hopper) --

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